The present invention relates generally to radiotelephone communications and in particular to acoustic sealing of portable radiotelephone speakers.
In radiotelephones, a user communicates by means of a handset (see U.S. Pat. No. Des. 286,778) that includes a speaker at one end that is placed close to the user's ear and a microphone at the other end that is held close to the user's mouth. A portable radiotelephone incorporates the handset into the transceiver (see U.S. Pat. No. Des. 269,873).
A portable radiotelephone requires a good tight acoustic seal between the speaker and the portable radiotelephone housing for satisfactory acoustical performance, in particular for good low frequency response. At the same time, since the sound from the speaker causes the portable radiotelephone housing to vibrate if it is not acoustically insulated from the speaker, the acoustic seal must also insulate the portable radiotelephone housing from the speaker to prevent this vibration. If the speaker excessively vibrates the portable radiotelephone housing, the radiotelephone performance can be degraded to an unacceptable level. In some countries there is even a requirement specifying how much the speaker can move with respect to the portable radiotelephone housing to ensure the integrity of the acoustic seal and acoustic performance.
In a portable radiotelephone, this acoustic seal is typically implemented by a flat gasket that forms the interface between the speaker and the portable radiotelephone housing. It is bonded by adhesives to the speaker or housing, or to both the speaker and housing. This flat gasket also compensates for the dimensional tolerances of portable radiotelephone subassemblies in a direction axial to the plane of the gasket. This flat gasket seals the speaker only in the direction axial to the plane of the gasket. Alignment, and assembly in general, is not easy because adhesives do not allow easy placement and positioning of the speaker, housing, and gasket with respect to each other. To insure proper alignment during the assembly process, a special tool or fixture is often required. If there is misalignment, the adhesive seal makes repair and reassemble difficult. Moreover, this acoustic seal assembly requires that subassemblies of a portable radiotelephone to have very tight dimensional tolerances, otherwise misalignment and consequential repair become more probable.
Accordingly, there is a resulting need for a gasket that will allow easy assembly and disassembly of the acoustically sealed speaker, and also enable the other subassemblies of a portable radiotelephone to accept wider dimensional tolerance windows that can be compensated by the gasket in the acoustic seal.